The structure of a conventional electronic cigarette is shown in FIG. 1. The conventional electronic cigarette includes an atomizer 110 and a battery assembly 120 which are connected to each other. The electrodes of the battery assembly 120 are coaxial with the electrodes of the atomizer 110. The electrodes of the battery assembly 120 include a lower electrode copper part 121 and an internally threaded copper part 122, which are connected to a positive electrode and a negative electrode of a battery, respectively. The electrodes of the atomizer 110 include an upper electrode 111 and an externally threaded electrode 112. The upper electrode 111 and the externally threaded electrode 112 are electrically connected to an electrical heating wire 113 of the atomizer 110. When the atomizer 110 is connected to the battery assembly 120, the lower electrode copper part 121 of the battery assembly 120 is electrically connected to the upper electrode 111 of the atomizer 110, and the internally threaded copper part 122 of the battery assembly 120 is electrically connected to the externally threaded electrode 112 of the atomizer 110, thus, a closed loop is formed, and the battery assembly 120 can provide power to the electric heating wire 113 of the atomizer 110 to generate smoke.
Contacting portions of the lower electrode copper part 121 and the upper electrode 111 are in an annular surface contact, as well as contacting portions of the externally threaded electrode 112 and the internally threaded copper part 122. The upper electrode of the atomizer 110 is of a hollow structure. When a user smokes the electronic cigarette, the airflow passes through a cavity. The lower electrode copper part 121 of the battery assembly 120 is of a hollow structure. When the atomizer 110 is connected to the battery assembly 120, the position of the cavity of the upper electrode 111 is corresponding to the position of the cavity of the lower electrode copper part 121, and the cavity of the upper electrode 111 is in communication with the cavity of the lower electrode copper part 121, thereby forming an airflow passage of the electronic cigarette. When the electronic cigarette is used for a long time, the cigarette liquid in the atomizer 110 is prone to flow from the cavity of the upper electrode 111 into the battery assembly 120 through the cavity of the lower electrode copper part 121 due to the gravity or capillary action, which may cause a short circuit of the battery assembly 120, and further reduces the service life of the electronic cigarette. Further, in order to increase the air quantity and decrease the heat generated by the atomizer 110 in operation, the externally threaded electrode 112 of the atomizer 110 is provided with an inlet hole 114, and the end surface of the upper electrode is provided with a vent groove 115 transversely which is in communication with the cavity and the inlet hole 114. However, when the atomizer 110 is connected to the battery assembly 120, the end surface of the upper electrode 111 abuts against the end surface of the lower electrode copper part 121. Thus, the vent groove 115 is prone to be blocked by dirt formed by the leaked cigarette liquid contaminated by dust, which blocks the airflow passage, and further causes users being short of breath when smoking the electronic cigarette.